We propose to emulate and model key mechanical and biochemical conditions of developing heart valves towards the ultimate goal of creating a robust tissue engineered heart valve (TEHV). We hypothesize that growth factors critical to embryonic valve development regulate valve interstitial cell (VIC) extracellular matrix (ECM) synthesis and remodeling in a tension- dependent manner. We propose that a quantitative understanding of growth factor-tension interactions will reveal conditions which stimulate VICs to produce tissues with high glycosaminoglycan (GAG) content that resist shortening. To test our hypothesis, VICs will be cultured in small-scale tissue models made from natural proteins which allow for control over tension generated by the cells and rapid analysis of tissue mechanical and biochemical properties in a high-throughput manner. We will quantitatively assess the effect of tissue tension and combinations of exogenous addition of transforming growth factor-beta1, epidermal growth factor, and bone morphogenetic protein-2 on tissue mechanics and composition and model the balance between ECM secretion and degradation computationally. The results from this systematic study will have a direct impact on tissue engineered heart valve (TEHV) development by determining optimal culture conditions for robust tissue formation with minimal shortening. The findings will also increase our understanding of how growth factors and mechanical stimuli coordinate valve development and repair and lead to pathological remodeling. The approach of creating immature tissue under low tension based on embryonic valve development is an innovative departure from standard TEHV fabrication paradigms.